Many systems have been developed to assist in the purification of water and other fluids. Many of these systems use active carbon filters or other filters of a mechanical nature to remove chemicals and other particular matter, including micro-organisms. Such filters, while capable of removing certain particular matter and chemicals, are not completely satisfactory for the purification of fluids and water containing bacteria type of contaminents.
It is well known that the exposure of water of fluids to ultraviolet radiation kills many micro-organisms and bacteria. One such ultraviolet purification system is disclosed in U.S. Pat. No. 4,769,131 entitled "Ultraviolet Radiation Purification System," and issued on Sep. 6, 1988. This patent discloses a water purification system using an ultraviolet lamp, and it is directed to two independent fluid conduits that are coiled about an ultraviolet lamp. The conduits are transparent permitting the ultraviolet energy to radiate the fluid flowing within the two conduits. Accordingly, any micro-organisms or bacteria present in the fluid so treated will be killed. In order to kill the micro-organisms contaminating water, a specific quantity or level of ultra-violet radiation must be maintained in order to effectively rid the contaminating micro-organisms from fluid or water being treated. The lamp, therefore, must provide the optimum amount of ultraviolet energy to kill the micro-organisms during the maximum rated fluid flow.
Heretofore, in ultraviolet water purification systems, in order to maintain the system in its optimum purification mode of operation, the energy source, i.e. the ultraviolet lamp was operated at its optimum operating mode regardless of the amount of fluid flow. Thus, at low flow or not flow rate, the ultraviolet lamp was maintained in its operating mode. The ultraviolet energy source or lamp was so maintained because the cycling of the lamp between "on" and "off" materially affected or shortened the useful life of the lamp.
In systems where the fluid flow was subjected to frequent intermittent flow operation, e.g. drinking water and/or other types of demand use situations, it was noted that the heat generated by the energized ultraviolet lamp source would be transmitted to the fluid or liquid being treated. In a low flow or no flow situation, the standing or slow moving water in the vicinity of the U.V. source or lamp would become highly heated, a very undesirable situation in the case of drinking water. The problem is even more aggrevated during long periods of non flow of such water or fluid.
In applications involving frequent uses for short durations, the cycling on and off of the ultraviolet lamp has proven to shorten the lamp's life. Therefore, it is advantageous to eliminate as much as possible, the on and off cycling of the UV lamp.
In other systems, e.g. as disclosed in U.S. Pat. No. 4,767,932, successive banks of ultraviolet lamps were disposed in the path of fluid flow wherein the amount of ultraviolet radiation generated was determined by the number of lamp banks that were energized in accordance to fluid flow. Systems of this type have been utilized to treat waste fluids. In such systems, it was still necessary to subject the lamp to an on-off cycle, even though the lamps were actuated in banks.